How to make package installs faster

[SamEdwardes]

• Add something to init.sh to set up all virtual environments in advance
• Update the uvsync alias to not call compile, and instead just sync. Compile only needs to be run when requirements.in changes.
• Add a cache that is shared by all users, I think we would have to rebuild docker image for this... but maybe not. Maybe it could be in /home/.uv-shared-cache?. Can you uv check here first, and then look at users cache?